OFFSET
1,1
EXAMPLE
a(14) = 10253 belongs to the emirp pair (10253, 35201) whose average is the prime 22727 = A178581(14) which is also the arithmetic mean of the other emirp pair (11243, 34211).
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Lekraj Beedassy, May 29 2010
STATUS
approved